Air conditioning system



Dw 1941- A. B. NEWTON 2,266,238]

AIR CONDITIONING SYSTEM Fild Feb. '7, 1958 2 Sheets-Sheet z T HIGH Ll MIT' CO NTROLS 23 INVENTOR lwin B. Newlbn ATTORNEY- Patented Dec. 16,1941 UNITED STATES PATENT OFFICE AIR CONDITIONING SYSTEM Alwin B.Newton, Minnea Minneapolis-Honeyw polis, Minn., assignor to ellRegulator Company,

Minneapolis, Minn., a corporation of Delaware Application February7,1938, Serial No. 189,082

23 Claims.

This invention relates in general to air conditioning systems and ismore particularly concerned with air conditioning systems of the typewhich are adapted to cool a space during the summer and to heat a spaceduring the winter.

The primary object of my invention lies in the provision of a novelyear-around air conditioning system which is adapted to automaticallymaintain the proper temperature and humidity withuin a conditioned spaceat all times. More specifivision of a system of this tyge with a heatengine iwpe of prime mover such as an internal combustion engine, andthe provision of means for automatically cooling the engine andcondenser when the system is operating on the summer cycle, and fortransferring heat from the engine and condenser to the space when heatis necessary for maintaining proper conditions within the space.

Another object isin the provision of a system of this type with aneasily controlled and efiicient arrangement for transferring heat fromthe exhaust gases of the internal combustion engine to the spaceand/orfor transferring waste heat from the engine to a supply ofdomestic water for heating the same.

In systems of this general type wherein heat is pumped from outside'intothe space by means of a, reversed refrigeration system, the capacity ofthe system tends to decrease as the outdoor temperature falls.Heretofore, this has limited the application of installations of thischaracter to locations in mild climates. It is a further object of myinvention to provide a system of this type which may be utilized insevere climates as well as in mild climates, thereby enabling theadvantages and economy of reversed cycle systems to be had in severeclimates where economy in heating is mportant factor. In accoid ancewith my invention, this result is achieved by the use of an additionalheating device which is driven by the internal combustion engine which 7drives the refrigeration compressor, and which remains out of operationas long as the reversed cycle system remains efiective, but whichreplaces the reversed cycle system for supplying heat and for loadingthe engine when. the reversed cycle system becomes ineffective.

Another factor which has limited the commercial development of reversedcycle systems 1 and 2.

is the initial cost of systems of this character. Due to systems of thistype requiring considerably more apparatus than other types of systemssuch as steam, hot water, or hot air systems, reversed cycle systemshave not been commercially feasible. It is an object of my invention toprovide an arrangement for considerably lowering the initial costs ofsystems of the reversed cycle type. This object is achieved by theprovision of an auxiliary heating device for supplying additional heatto the system, and a control mechanism for placing this auxiliary heaterin operation during peak load conditions. By this arrangement, theinstallation may be made considerably smaller than would be necessaryfor carrying peak loads which occur during only a very small part of theheating season.

A further object of this invention is the provision of a simple andeffective automatic control system for systems of the type mentioned,which provides for maintaining proper temperature and humidityconditions within the conditioned space. i

Other objects of my invention lie in various sub-combinations formingpart of the complete system, and will become apparent from the followingdescription and the appende'dclaims.

- For a full disclosure of my invention, reference is made to thefollowing detailed description and to the accompanying drawings inwhich:

Figure 1 shows diagrammatically one form which my invention may take;

- Figure 2 illustrates diagrammatically a rmodisystem shown in Figure1'; and

fication of the in which Figure 3 shows a modified form of exhaust gas Iheat utilizing means which maybe employed in-v Q dependently or with thesystems shown in Figures Referring to Figure 1, reference character]indicates a conditioning chamber having a fresh air inlet 2 and a returnair inlet 3 which conducts air from a space being conditioned to thechamber l. The discharge end of the conditioning chamber I is connectedto the inlet of a fan 4, which in'turn isconnected to a discharge duct 5for conveying conditioned air to the space being conditioned; Within thechamber I is located a direct expansion cooling coil 6, a condenserheating coil 1, a jacket water heating coil 8, and an exhaust heatingcoil 9. Also located within the conditioning chamber I is a humidifierIII which may take the form of a water pan having a heating coil locatedtherein. The humidifier ll may be provided with a water supply pipe I2and a float valve I3 for maintaining a predetermined water level withinthe water pan. Also located within the conditioning chamber I is anelectric strip heater I4.

The direct expansion cooling coil Ii forms a part of a refrigerationsystem including a compressor l5. The discharge line l6 of thecompressor leads to a condenser II for condensing the compressedrefrigerant discharged by the compressor. The condensed refrigerantpasses from the condenser I'I into a receiver I8 and from this receiverpasses through a liquid line I9 which leads to a pair of solenoid orelectrically controlled valves and 2|. The outlet of valve 2| isconnected by means of a pipe 22 to an expansion valve 23 which'islocated at the inlet of the evaporator coil 6. This expansion valve maybe of any desired type having a bulb 24 connected Y to the evaporatoroutlet pipe 25. The pipe 25 is in turn connected to a pipe 26 whichleads to the compressor inlet. The valves 20 and 2| are arranged to bealternately opened or closed by means of a control device which will bedescribed hereinafter. Hence when the valve 2| is opened, the valve 20will be closed. Under these conditions, it will be apparent that liquidrefrigerant will flow from the receiver I8 through the expansion valve23 into the cooling coil 6, thereby causing chilling of this coil andevaporation of refrigerant within the coil, the evaporated refrigerantpassing back to the com- When the valve 20 is opened and the valve 2| isclosed, however, liquid refrigerant will flow through valve 20 and pipe21 to an expansion valve 28 which is located at the inlet of an outsideevaporator coil 29 and will flow from this coil through a pipe 30 to thecompressor inlet pipe 25 and hence back to the compressor. This actionwill cause heat energy to be absorbed by evaporation of the refrigerantwithin the evaporator 29, this heat then being supplied to the condenserII from which it will be transmitted to the heating coil I in a mannerwhich will be described hereinafter.- The outside evaporator, it will beunderstood, may be subjected to outside atmosphere, may be placedunderground, or may takethe form of a heat exchanger through which well.water or other heat-- ing medium is passed. From the description thusfar it will'be apparent that the compressor I5, condenser I1, andevaporators 6 and 29 constitute a reversible cycle refrigeration systemwhich is adapted to cool the air whenever the valve 2| is opened andwhich is adapted to heat the air whenever the valve 20 is opened.

During the heating cycle of the system; it is necessary to transfer heatfrom the condenser II to the heating coil I which is located within 'theconditioning chamber.

For this purpose a circulating pump 3| is provided. This pump may bedriven by an electric motor 32 or if desired may be driven by the sameprime mover which drives the compressor I5. The pump 3| is connected toa discharge pipe 33 leading to a check valve 34, which in turn isconnected by a con uit 35 leading to the condenser |I.- The coolinmedium outlet of the condenser |I is connected by a pipe 38 to a heatexchanger 31, the cooling medium passing through this heat exchangerinto a conduit-38 which is connected by a pipe 39 to the inlet of thepump 3|. By this arrangement, it will be apparent that cooling medium iscirculated by the pump 3| through the condenser and the heat exchanger31 for thereby transferring heat from the condenser to the heatexchanger 31.

The heat exchanger 31 is provided with a heating coil 48. One end ofthis heating coil is connected by a pipe 4| to the inlet of the coil Iwhich is located within the chamber l. The outlet of the coil I isconnected to an electrical control valve 42, the outlet of this valvebeing connected by a pipe 43 to'the inlet of the coil 40. Coils 40 and Iare therefore connected together for forming a closed circulatorysystem. This system may be charged with a volatile fluid such as alcoholor ether. When the valve 42 is opened, this volatile fluid will beevaporated within the coil 40, thereby cooling the heat exchange mediumbeing discharged from the condenser. The evaporated fluid will then passthrough the pipe 4| to the heating coil I wherein it will condense,thereby giving up the heat absorbed from the condenser to the airpassing over coil I. The"condensed fluid will then pass through thevalve 42 and pipe '43 backto the coil 40 for re-evaporation. When thevalve 42 is closed, however, condensed volatile fluid will be trappedabove the valve 42 thereby filling or partially filling coil 1 withcondensate and also preventing any condensate from entering the 'coil40. This will in turn partially or completely place .the heat exchangerI out of operation, depending upon the length of time that valve 42 isclosed. By this arrangement, the valve 42 handles only a small quantityof condensed fluid and hence this valve may be relatively small.

During the cooling cycle of this system, the valve 42 will be normally010m and hence no heat will be transferred from the condenser to theheating coil I. At this time, the condenser will be cooled by thepassage of water from an outside source, such as a cooling tower,through the condenser. This arrangement will now be described. Referencecharacter 45 indicates an electrical control valve, the inlet of whichmay be connected to a suitable source of cooling medium, such forinstance as a cooling tower or a water main. The outlet of this valve isconnected by a pipe 46 to the pipe 35 which leads to the condenser II.While the valve 45 may be controlled in various manners in accordancewith my invention, I prefer to control this valve by means of a pressurecontroller 41 which is responsive to the pressure of the compressedrefrigerant. This pressure controller may consist of a bellows 43 whichis connected by a tube to the high pressure refrigerantline I6. Thisbellows may actuate a pivoted mercury switch carrier which carries amercury switch 43 which is connected in series with the valve 45. Thiscontroller may be so designed and adjusted as to maintain the mercuryswitch 43 open so long as the pressure of the compressed refrigerant isbelow the value prevailing when the heating coil I is in operation whilecausing closing of the mercury switch 43 and consequent opening of thewater valve 45 whenever the refrigerant pressure exceeds this value.When the system is operating on the heating cycle, heat will betransferred from the condenser to the heating coil I in such quantitiesas to prevent the pressure of the compressed refrigerant from risingabove the setting of the'pressure controller 49 and consequently thevalve 45 will be closed for preventing the supply of outside coolingwater to the condenser. However, when the system is operating on thecooling cycle, closure of the valve 42 will prevent heat from beingtransferred from the condenser to the heating coil 1. This will resultin the temperature of the condenser cooling medium rising, which will befollowed by a rise in pressure of the condensed refrigerant. Thispressure will continue to rise until it reaches the setting of thepressure controller 41 and .causes this controller to close the mercuryswitch 49 for opening the water supply valve 45. Cooled water from anoutside source will then flow through the pipes 46 and 35 into thecondenser for condensing the refrigerant. This condenser cooling waterwill then pass through the pipe 36 into the heat exchanger 31 and fromthe heat exchanger 31 to the pipe 38, and will flow from pipe 38 througha relief valve 50. The cooling medium discharged through the reliefvalve 50 will then be either returned to the cooling tower, if such isused, or will be wasted. It will be understood that the relief valve 50will-be loaded sufficiently to prevent opening thereof unless the valve45 is opened. Consequently, whenever the valve 45 is closed, the reliefvalve 50 will close for maintaining the condenser cooling circuit closedat such time.

Referring to the compressor I5, this compressor may be driven by meansof an internal combustion engine This engine may be provided with theusual exhaust manifold 52, intake manifold 53, starting motor 54, andgenerator 55. This engine may also be provided with a throttle valve orother type of speed or out-put controller 56. The engine 5| may drivethe compressor l5 by mean's of any suitable power transmission means,such means being illustrated herein as comprising a drive shaft 51,pulleys 58 and 59, and cooperating belts 60.

In accordance with my invention, provision is made for utilizing thewaste heat of the engine for supplementing the effect of the reversecycle refrigeration system in heating the space during the heating cycleof the system, and for providing reheat when necessary during thecooling cycle. In order to transfer heatjrom the cylinder walls of theengine to the air being conditioned, a jacket water heat exchanger 6| isprovided. This jacket water heat exchanger 6| is connected to the outletof the engine water jacket by means of a pipe 62 which may haveinterposed therein a thermostat 63 for preventing overcooling of theengine. The outlet of the exchanger 6| is connected to the pipe 38 whichleads to the circulating pump 3|, and the discharge of the circulatingpump 3| is connected to the engine water jacket by means of a pipe 64.By this arrangement, hot water is circulated from the engine waterjacket through the heat exchanger 6| and is returned to the engine waterjacket by means of. the circulating pump 3|. The circulating pump 3|,therefore, acts to cause both a circulation of cooling water through thecondenser l1 and the heat exchanger 40, and a circulation of coolingwater between the engine water jacket and the heat exchanger 6|.

inlet of the coil 65, an electric control valve 69 being interposed inthis conduit. The arrangement just described forms a closed heattransfer system, and this system may be charged with a volatile fluid.When the valve 69 is opened,v

liquid volatile fluid will be allowed to enter the coil 65. This willevaporate within the coil 65 thereby cooling the water being dischargedfrom the engine into the heat exchanger 6|. The evaporated fluid thenpasses to the heating coil 8 wherein it condenses and gives up its heatto the air flowing across coil 8. The condensed or partially condensedvolatile fluid will then pass from the coil 8 through pipe 61 intoheating coil II in the humidifier pan, and will give up its re-,

this exchanger 10 being connected to an exhaust The heat exchanger 6|isprovided with-a coil 65.- The outlet of this coil 66 iscon'nected by aconduit 6.6 to the inlet of the jacket water heating coil 8 which islocated ,within'the conditioning'chamber'l. The outlet of coil 8 isconnected by" a conduit 6'| to the heating'coil l l locatedthehuniidifier pan'and' the outlet of this coil'i's connectedby'meansota-oonduit 66 to the pipe H, which in turn is connected to the exhaustmanifold of the engine. The exhaust gases from the engine pass over acoil 12 which is located within the heat exchanger 10. The coil 12 maybe connected by a pipe 13 to the inlet of the exhaust heating coil 9which is located within the conditioning chamber, and the outlet of thelatter coil may be connected by pipe 14 'to the inlet of coil 12,thereby forming a closed heat transfer system. This system may also becharged with a volatile fluid for thereby transferring heat from thecoil I2 to the coil 9. Similarly, to the other closed heat transfersystems described, this heat transfer system may be provided with acontrol valve 15 for preventing the transfer of heat from coil 12 to theheating coil 9.

If desired, the exhaust gases may be also utilized for heating domesticwater. For this purpose a domestic hot-water tank 16 having a heatingcoil 11 may be ,utilized. In order to prevent overheating of thedomestic water, a three-way valve 18 may be interposed between theexhaust pipe 19 and the heating coil 11, this valve also being connectedto a by-pass -for by-passing exhaust gases around the coil TI. The valve18 may be controlled by means of a thermostat 8| which is responsive tothe temperature of the domestic hot water.

stat 8| may include a bellows '82 which is connected by a capillary tube83 to a control bulb 84 located within the tank I6. This bellowscooperates with a pivoted mercury switch carrier' position the mercuryswitch 65 for causing'the valve 18 to pass all of the exhaust gasesthrough the heating coil 11. When the domestic water- The thermo- Itemperature becomes excessive, however, the bellows will expand, tiltingthe mercury switch 85 to the position shown for thereby causing thevalve I8 to by-pass the exhaust gases around the heating coil 11-.

With a reversed cycle' heating system as described, it will be apparentthat as the outdoor temperature becomes colder, less and less heat willbe picked up by the outside evaporator. This will result in lessevaporated refrigerant being returned from the outside evaporator 29 tothe compressor which will, in turn, result in decreasing the load on thecompressor. This action will, in turn, reduce the load applied upon theengine and consequently the waste heat given off by the engine will belowered. Thus at the very time that more heat is necessary for heatingthe space, the system will tend to become unloaded thereby actuallysupplying a smaller quantity of heat than at times when the heating loadis relatively light. In order to avoid this shortcoming of a reversedcycle heating system, I have provided for loading the engine 5| wheneverthe reverse cycle refrigeration system becomes ineffective for heatingthe space. This arrangement will now be described. Reference character99 indicates an electric generator which is driven by the internalcombustion engine through the medium of pulleys 9| and 92 over vwhichrun belts 93. The pulley 92 is preferably provided with a suitableelectrically controlled or magnetic clutching device which is controlledby wires 94 and 95 for thereby selectively connecting the generator tothe engine shaft, or for disconnecting the generator therefrom. Thegenerator 99 may be connected by wires 96 and 91 to the strip heater I4which is located within the conditioning'chamber. It will be apparentthat whenever the clutch forming a part of pulley 92 is engaged, thegenerator 99 will be rotated by the engine, thereby loading the engine5| and supplying energy to the strip heater I4. Thus, the additionalload upon the engine is utilized for heating the space. Due to thethrowing of this electric heater load upon the engine 5|, the

waste. heat given off by the engine will be increased and consequentlymore heat will be supplied to the air by the heaters 8 and 9. Hence,when the clutchis engaged the heat out-put of the system will beconsiderably increased thereby providing for heating the space despitethe fact that the outside temperature may fall so low as to make thereversed cycle heating system 'inefiective.

In accordance with my invention, I also provide for supplying outsideheat to the syst whenever the system becomes incapable of heating thespace by the action of the internal combustion engine alone. For thispurpose, a gas or other suitable type burner I99 may be located withinthe exhaust gas heat exchanger I9. This gas burner may be controlled bymeans of a motorized gas valve I9I, which in turn, is controlled by thecontrol mechanism which will be hereinafter described. My invention alsoprovides for automatically controlling the system just described in amanner to provide for mainto open the throttle valve 56 wider.

taining proper temperature and humidity oonwhich will now be described.

character I95 indicates generally a low limit thermostat which may belocated within the space being conditioned or in thereturn duct 8. Thisthermostat may be of any desired This actionis obtained by the conby apotentiometer type of controller and assumes intermediate positionscorresponding to the position of the potentiometer slider upon thepotentiometer coil. In the present instance, the

thermostat I95 is connected to the proportioning motor I I9 in a mannerto cause clockwise rotation'of its operating shaft III as the slider I98moves to the right across the resistance I99. Hence, upon a decrease inspace temperature, the bellows I99 of the thermostat I95 will contract,thereby causing movement of the slider I98 to the right across theresistance I99 which will be followed up by a clockwise movement of themotor shaft III. The thermostat I95 may be so designed as to causeengagement of the slider I98 with the extreme left-hand end ofresistance I99 when the space temperature rises to 74 F., and to engagethe extreme right-hand end of said resistance when the space temperaturefalls to F. Hence, by this arrangement the motor shaft III will assumean extreme counter-clockwise position when the space temperature is ator above 74 R, will gradually shift clockwise upon fall in temperature,and will reach its extreme clockwise limit of rotation when the spacetemperature falls as low as 79 F.

The various control valves 29, 2|, 42, 69, I5, and IM are preferably ofthe type which remain closed when deenergized and' which open whenenergized. These valves and the magnetic clutch of generator pulley 92are controlled by means of a series of mercury switches H5, H6, H1, H8,H9 and I29 which are actuated sequentially by means of a series of cams|2|, I22, I23, I24,

I25, and I26 which are'mounted upon the motor shaft I I I. These camsare arranged on the shaft III in a manner to cause sequential closing ofthe mercury switches in the order named as the shaft III rotates in aclockwise direction and to cause these switches to be tilted toopenposition ranged to control a proportioning motor I8! which is arrangedfor actuating the throttle valve 56. As will be more completelydescribed later, the movement of the slider I2'I in a clockwisedirection across the resistance I28 will have the effect of causing theproportioning motor I'8I Therefore, this arrangement will provide forincreasing'the engine speed upon a decrease in space temperature.

Preferably, the engine 5| is provided with an arrangement for causingautomatic starting of the engine whenever the throttle valve is openedand for stopping the engine whenever the throttle valve 58 is moved toclosed position by its controller. For this purpose the proportioningmotor I8| may be provided with an auxiliary 1 switch I82 which isillustrated herein as helm:

of the mercury type which is actuated by means changes in temperature.

temperature, the bellows I52 will expand thereby of the actuating leverI33 of the proportioning motor. This switch is so mounted upon the leverI33 as to be tilted to closed position whenever the throttle valve 56 isopened slightly, and is arranged to be tilted to open position wheneverthe throttle valve 56 is closed beyond this-point. The mercury switchI32 is arranged to control an automatic starting circuit for the enginewhich will now be described. Reference character I34 indicates a storagebattery, one terminal of which may be grounded as shown. The otherterminal of the storage battery I34 is connected to the switch I 32 bymeans of wire I35, and the switch I32 is also connected to the controlterminal of a starting relay I36 by means of wire I31. This startingrelay may'be of the type shown in Patent No. 1,773,913 issued to L. K.Loehr et a]. on August 26, 1930. This type of starting relay is arrangedto energize the starting motor whenever the control circuit for therelay is energized, and for this purpose the starting relay I36 isconnected to the starting motor 54 and to the storage battery I34 bymeans of wires I38 and I39; The wire I31 which leads from the mercuryswitch I32 to the control terminal of the starting relay is alsoconnected to the engine ignition coil I40. Hence, when the mercuryswitch I32 is closed by opening movement of the throttle valve 56, theignition circuit for the engine will be completed, and also the startingrelay willbe energized for complet-.

ing a circuit from the battery through the starting motor, therebycranking the engine. This starting relay is also arranged to deenergizethe starting motor automaticallywhen the engine starts, as indicated bythe starting motor taking less current. This relay is also arranged in amanner to prevent energization of the starting motor so long as theengine is in operation, as indicated by operation of the generator. Forthis purpose the starting relay is connected to the generator 55 bymeans of a wire I. The generator 55 is also connected to the battery I34through a reverse current relay I42 in the usual manner. By thearrangement just described, whenever the throttle valve 56 is opened,the ignition circuit for the engine will be completed and the startingmotor will be caused to operate until the engine is started, at whichtime it will be automatically deenergized. The engine I will thencontinue to operate until the throttle valve 56 is closed therebyopening the mercury switch I 32 and breaking the ignition circuit.

The throttle valve motor I3I is also arranged to be controlled by meansof a high limit space thermostat I50 and a high limit humiditycontroller I5I. Referring to the thermostat I50, this thermostat may belocated either within the conditioned space or within the return duct 3.

This controller may be of any desired type and is illustrated ascomprising a bellows I52 cooperating with a bell-crank lever having anactuating arm I53 and a control arm or slider I54 which is arranged toengage a resistance I55 for forming a control potentiometer. The bellowsI52 contains a suitable volatile fluidand-conse quently this bellowsexpands and contracts with Upon an increase in rotating arm I53 in acounter-clockwise direction against the action of spring I56, thusshift-.

ing the slider I 54' to the left across the resistance I55. Upon adecrease in temperature, the

' I59. The slider I59 in turn is adapted to engage a resistance I60 forforming a control potentiometer. Upon a decrease in relative humidity,the strands I51 willshrink thereby causing a counter-clockwise movementof the bell-crank lever against the action of a spring I6I, thusshifting the slider I59 to the right across resistance I60. As therelative humidity increases,

however, the strands will increase in length thereby permitting thespring I6I to shift slider I59 to the left. This instrument may be sodesigned and adjusted as to cause the slider I59 to engage theright-hand end of resistance I60 when the relative humidity falls below40%, while engaging the left-hand end of said resistance when thehumidity rises to 60%.

The proportioning'motor I3I is preferably of the type shown anddescribed in the Taylor patent previously mentioned. Upon reference tothis patent, it will be noted that this type of proportioning motor isprovided with three control terminals and which are herein marked as R,B and W. The motor is adapted to assume positions corresponding to therelative values of the resistance connected between terminals R and Band between terminals R and W. For instance, if the resistanceinterposed between terminals R and B is exactly equal to the resistanceinterposed between terminals R and W, the motor will assumemid-position. If the terminals R and B should be substantiallyshort-circuited, however, while resistan'c is interposed betweenterminals R and W, the otor will run to an extreme position at which themotor valve is wide open. On the other hand, should the terminals R andW be short-circu-ited while resistance is interposed between terminals Rand B, the motor will run to its other extreme position at which thethrottle valve is completely closed. For intermediate relationshipsbetween the resistance which is connected between terminals R and B andR and W, it will be understood that the motor I3I will assumeintermediate positions corresponding to the relationship between theresistances.

The type of proportioning motor just described is, of course, adapted tobe controlled by means of one or more potentiometer type of controllers,and in accordance with my invention, the throttling valve motor BI iscontrolled by the conjoint action of the high limit space thermostatI50, the high limit humidity controller I5I, and the potentiometerformed by slider I21 and resistance I28 which is actuated-by the lowlimit space thermostat I05 through the medium of the proportioning motorIIO. Referring to the connections between the motor I3I and the variouscontrol potentiometers, it will be noted that terminal R of the motor isconnected by wire I65 to the slider I54 0! the high limit controllerI50. The terminal B of the motor is connected by wires I66, I61, I68,and I69 to the left-hand tact segment I which is joined to the lower endof resistance I28. The terminal W of the motor is connected to the upperend of resistance I28 through the contact segment I29 by means of wireI10. The right-hand end of the resistance I55 is connected to the sliderI59 by means of wire I1 I, and the right-hand end of resistance I60 isconnected to the slider I21 by wire I12.

With the sliders I21, I54 and I59 in the posi tion shown, the spacetemperature is approximately 78.5 as indicated by the slider I54engaging the center of resistance I55. For this value of temperature,the slider I21 is engaging the upper end of contact segment I29 due tothe proportioning motor IIO having been rotated to its extremecounter-clockwise position. Also, the space relative humidity is belowas indicated by the slider I59 of the humidity controller engaging theright-hand end of resistance I60. With the sliders I21 and I59 in thepositions shown, the high limit thermostat I will be placed in fullcontrol of the motor I3I. It will be noted that the slider I54 of thiscontroller is directly connected to terminal R of the motorand theleft-hand end of resistance I55 is connected directly to terminal B ofthe motor by wires I66 and I61. The right-hand end of the resistance I55at this time is connected to terminal W of the motor as follows:terminal W,

wire I10, segment I29, slider I21, wire I12, slider I59, and wire In tothe right-hand end of resistance I55. It will now be apparent that theslider I54 of the thermostat I50 is dividing the resistance I55 into oneportion which is connected across terminals R and B of the motor andinto another portion which is connected across terminals R and W of themotor. Due to the resistances connected across the motor being equal,the motor has assumed mid-position in which the throttle valve 56 ishalf open as shown.

If the space temperature should increase, the slider I54 will be shiftedto the left across re-. sistance I55 which will decrease the portion ofthis resistance which is connected across terminals R. and B and willincrease the portion of the resistance which is connected acrossterminals R and W. In response to this change in relationship betweenthe resistances connected across the motor terminals, the motor willrotate its operating lever I33 in a clockwise direction an amountcorresponding to the movement of the slider I54 across the resistanceI55. This will shift the throttle valve 56 to a further open pos tionand thus increase the speed of the engine. This, in turn, will causemore cooling to be done by the system for counteracting the rise intemperature. Conversely, should the space temperature fall, the sliderI54 will be shifted to the right across resistance I55 therebydecreasing the resistance connected between terminals R and W andincreasing the resistance connected between terminals R and B. This willcause movement of the motor I3I in the opposite direction for moving thethrottle valve 56 to a further closed position, thus decreasing theengine speed i to counteract the drop in temperature. From theforegoing, it should be apparent that when the space temperature isabove 15 F. and the humidity is at 40% or below, the high limit spacethermostat I50 will be in full control of the engine speed and willgraduatingly vary this engine speed in a manner tending to maintain theconstant space temperature. Due to the wide range of the controller I50,however, this controller will increase the space temperature must rise,and

consequently as the load on the system increases, the space temperaturemust rise to such a value that the controller I50 causes operation ofthe engine 5I at a speed which prevents further rise.

in temperature. Consequently, as the outdoor temperature increases, thetemperature maintained by the high limit space thermostat will beincreased.

The control arrangement disclosed will also cause operation of theengine in the event that the relative humidity becomes excessive andthis will occur even though the space temperature may be below thecontrol point of the high limit controller I50. A condition of this typeoften exists during cool damp weather. At this time, the slider I54 ofthe controller I50 will engage the right-hand end of resistance I55.This will connect terminal R of the motor I3I to the slider I59 of thehumidity controller as follows: terminal R, wire I65, slider I54, andwire I1I to slider I59. Terminal B of the motor I3I, it will be noted,is connected directly to the left-hand end of resistance I50 by wiresI65 and I60. Terminal W of the motor at this time is connected to theright-hand end of resistance I60 as follows: terminal W, wire I10,segment I29,'slider I21, and wire I12 to resistance I60. Therefore, atthis time the potentiometer of the humidity controller is operativelyconnected to the proportioning motor I3I for controlling the positionassumed by this motor. With the slider I59 in the posi-. tion shown atwhich the relative humidity is low, terminals R and W of the'motor willbe substantially short-circuited, while the entire resistance I60 willbe connected between terminals R and B. This would cause the motor I3Ito completely close the throttle valve 56 thereby preventing operationof the engine. If, however, the relative humidity increases, the sliderI59 will travel to the left across resistance I60 which will place aportion of the resistance I60 between terminals R and W and willdecrease the portion of the resistance which is connected betweenterminals R and B. This will cause the motor I3I to open the throttlevalve an amount corresponding to the movement of the slider I59 acrossres'istance I60. Therefore, the humidity controller I5I is capable ofcausing opening of the throttle valve and operation of the enginewhenever the relative humidity becomes excessive. The high limitthermostat I50 and the humidity controller I5I, therefore, cooperate incontrolling the throttle valve position, and the position assumed by thethrottle valve is determined by the conjoint action of these twocontrollers, the throttle valve being opened further upon an increase ineither temperature or humidity and being moved towards closed positionupon a decrease in values of these conditions.

I During the heating cycle of the system, therela'.ive humidity willusually be below 4%, and hence the slider I59 will engage the right-handend of resistance I60, as shown. Also at this.

time, the space temperature will be below F. and consequently the sliderI54 of thermostat I50 will engage the right-hand end of resistance I55.This action will connect the slider I21 of the winter controlpotentiometer to terminal R of the motor as follows: terminal R, wireI65, slider I54, wire I1I, slider I50, and wire I12 to slider I21.Terminal Wof the motor it will be noted, is connected to the contactsegment I20 by means of wire I10, and terminal B of the motor isconnected to the contact segment I30 by wires I66, I68, and I69. This,therefore,placesthe potentiometer formed of slider I21 and resistanceI28 in operative control of the proportioning motor I3I. At this time,it will be noted that resistances I55 and I60 are connected in parallelbetween terminals R and B of motor I3I. Thus resistance I55 is connectedacross terminals B and R as follows: terminal R, wire I65, slider I54,resistance I55, wire I61, and wire I66 to terminal B. The resistance I60will be connectedinparallel with resistance I55 by means of wire I1I,slider I50, and wire I68. These resistances being connected acrossterminals R and B would have the the engine speed when the spacetemperature begins falling below 72 F. and will modulate the enginespeed in a manner tending to maintain the space temperature betweenlimits of 72 F. and 70 F. The control arrangement just described,therefore, will cause operation of the engine whenever the spacetemperature rises to a value indicating that cooling is necessary or.

effect of crowding the operating range of the potentiometer formed ofslider I21 and resistance I20 towards one end of resistance I28. Inorder to avoid this result and thereby obtain closer control, the effectof resistances I55 and I60 is balanced out by means of resistance Iwhich is connected between terminals R and W.

' This resistance I15 is made equal in value to the combined parallelresistances I55 and I60 and consequently completely balances the effectof these resistances on the proportioning motor I3 I.

As pointed out previously, the s 'der I21 is rotated in acounter-clockwise directi n upon a decrease in space temperature. Withthe low limit controller I05 in the position shown, the spacetemperature is at or above 74 F., and consequently the motor shaft IIIis in its extreme counter-clockwise limit of rotation at which theslider I21 engages the upper end of segment I20. For this value of spacetemperature, the.

terminals R and W of the motor I3I will be substantially short-circuitedwhile the resistance I28 will be connected across terminals R and B.This would cause the motor I3I to completely close the throttle valve 56and place the engine 5I out of operation. As the space temperaturebegins falling, the motor shaft III will be rotated clockwise. However,until the space temperature falls to 72 F., the slider I21 will merelycontact the contact segment I and no change in position of the throttlevalve motor will take place. If the space temperature falls below 72 F.,the slider I21 will begin contacting the resistance I28 and will placepart of this resistance between terminals R and W and will decrease theportion of this resistance which is connected between terminals R and B.This will cause the motor I3I to open the throttle valve 56 an amountproportionate to the movement of slider I21 across the resistance I28.Consequently, as the space temperature falls below 72 F., the engine 5|will be placed into operation and its speed will be increased uponfurther decrease in temperature below this value. When the spacetemperature falls to 70 F., the slider I21 will engage the lower end ofresistance I20 and come-'- quently will cause the throttle valve 56 tobe wide open. Upon still further decrease in temperature, the slider I21 will engage the contact segment I30. This will permit the throttlevalve to continue to remain in wide open position. From the foregoing,it will be seen that the low limit space thermostat I05 will takecontrol of falls to such a value as to indicate that heating isnecessary. Also, the engine will be placed into operation whenever thespace relative humidity becomes excessive. In addition, the engine speedwill be modulated in accordance with the requirements for cooling, forheating, or for dehumidification.

Operation of Figure 1 With the parts in the position shown, the systemis operating on the cooling cycle, as indicated by the slider I54 of thehigh-limit space thermostat engaging the center of resistance I 55. Thisin the manner just described has caused the motor I 3| to shift thethrottle valve 56 to half are connected in circuit with the valves 42,69,

} open, the clutch is disengaged and consequently the generator 90 isnot being driven at this time. The mercury switch I I8 at this time istilted for causing bridging of the right-hand electrodes thereof whichwill cause energization of valve 2| as follows: line wire I16,right-hand electrodes of mercury switch II8, wire I11, valve 2I, andwire I18 to ground I19. Therefore, at this time the valve 2| will beopened thus placing the air stream or summer evaporator 6 into operationfor cooling the air. Due to the valve 42 being closed, heat is not.absorbed from the condenser cooling water by the heat exchanger 31 andconsequently the pressure of the compressed refrigerant has risen to avalue which causes the pressure controller -41 to open the water supplyvalve 45, thereby supplying cooling water to the condenser and to theinternal combustion engine 5I, thus providing for condensing thecompressed refrigerant and for preventing the engine 5| fromoverheating. During this operation of the system on the cooling cycle,the engine speed will be increased upon increase in either temperatureor relative humidity and will be decreased upon decrease in value ofthese conditions in a manner to maintain proper comfort conditionswithin the conditioned space, as previously described.

In the event that the relative humidity should be excessive while thespace temperature is relatively low as occurs in cool damp weather, therelative humidity controller will cause operation of the engine 5.I fordehumidifying the air, even though no cooling is required. Due to thecooling humidifying action of the coil 6, the space temperature willbegin falling. When the space temperature begins falling below 14 F.,the low limit controller I will cause clockwiserotation of the shaftIII. The first action of this rotation. will be to close the mercuryswitch II5. Closure of this switch will energize the valve 42 asfollows: line wire I16, mercury switch II5, wire I80, valve 42, and wireI8I to ground. Energization of valve 42 will cause opening thereof whichplaces the heat transfer system between heat exchanger 31 and theheating coil 1 in operation. This will provide heat for reheating theair after it has been cooled due to the action of cooling coil 6. Theheater 1, it should be noted, is supplied with heat absorbed from thecondenser and internal combustion engine. Due to the cooling efiect ofheat exchanger 40 on the water circulated in the system, the coolingeffect of the condenser will be increased which will cause thecompressor discharge pressure to decrease, thereby causing closing ofthe water supply valve 45. This, therefore, provides for economy incooling water supply for the condenser and internal combustion engine asit reduces the necessary additional cooling water to a minimum.

The described control arrangement for the reheater coil 1 will providefor floating control of the effective area of the reheatercoil 1 inaccordance with the demand for reheat. Prior to the demand for reheat,it will be understood that the reheater coil 1 will be full ofcondensate due to the trapping of condensate therein by the closed valve42. Upon demand for reheat, the valve 42 will be opened in the mannerdescribed, thus allowing condensate to trickle from the coil into theboiler or heat exchanger 40. Due to this withdrawal of condensatefromcoil 1,

vapor will take the place of the withdrawn con- I densate, thus causinga portion of the coil area to become heated. If the demand for reheat islight, the space temperature will, rise suflioiently to cause the valve42 to be again closed before a large portion of the coil will be madeefiective. The coil will then begin refilling with condensate which willeventually result in reopening of the valve 42 due to falling spacetemperature. It will be apparent that the heavier the demand for reheatbecomes, the longer valve 42 will -remain open. Consequently, as theheat demand becomes heavier, the effective coil area will be increased.The control arrangement just described will therefore act to vary theeffective reheater coil area in accordance with demand for reheat.

Under normal conditions, the reheater coil 1 will be suflicient forsupplying the necessary reheat. If, however, an unusual condition shouldoccur requiring an extraordinary amount of reheat, the space temperaturewill fall further, thus causing shaft III to be rotated clockwisethereby closing the mercury switch II6 which energizes valve 69 asfollows: line wire I16, mercury switch II6, wire I82, valve 69, and wireI83 to ground. At this time, thevaive 42 will remain open thus placingthe entire surface of coil I in operation. Also at this time theeffective heating surface of the heating coil 8. will be varied in thesame manner as described in connection with coil 1, for maintaining aconstant temperature within the space.

lows: line wire I16, mercury switch II1, wire I84, valve 15, and wireI85 to ground. This will place the heating coil 9 in operation, and itsefiective area will be varied in a manner to supply the necessary reheatas previously described. From the foregoing, it will be apparent thatthe heating coils are operated in sequence, and the effective area ofeach is controlled in a manner to provide a graduating control of reheatover a very wide range.

As the weather changes from a value requiring cooling ordehumidification to a value requiring heating, the space temperaturewill begin falling and also the space relative humidity will be below40% and consequently the control arms of the sliders I54 and I59 of thecontrollers I and'I5I will engage the right-hand ends of theirrespective resistances, which in a manner previously described placescontrol of the throttle valve motor with the potentiometer formed ofslider I21 and resistance I28. As the space temperature continues tofall, the shaft I II will be rotated clockwise thereby sequentiallyclosing the mercury switches H5, H6 and H1 which will open valves 42,69, and 15 for conditioning the heating coils I, 8, and 9 for operation,thereby providing for transferring the condenser heat, the jacket heatof the engine, and the exhaust heat of the engine to the air. Until thespace temperature falls to 72 F., no heat for the space will benecessary. Until this occurs, the slider I 21 will continue to ride onsegment I29, and hence the engine will not be placed into operation.Also the mercury switch II8 will remain in the position shown whichcauses energization of the valve 2I and deenergization of valve 20 whichwill permit the system to operate on the cooling cycle under control ofthe high limit humidity controller in the event that the humidity shouldbecome excessive. However, when the space temperature falls to 72 F.,the mercury switch I I8 will be tilted to its other position therebydeenergizing the valve 2I for placing the air stream evapor tor out ofoperation. This will also cause en rgization of valve 20 as follows:line wire I16, left-hand electrodes of mercury switch II8, wire I86,valve 20, and wire In the event that heating coils 1 and 8 should IIIwill rotate still further for closing mercury switch II1, which willenergize valve 15 a fol- I81 to ground. This will result in opening ofthe valve 20 for placing the outside evaporator 29 into operation.Therefore, when the space temperature falls to 72 F., the action of therefrigeration system will be reversed from cooling to heating. As thespace temperature falls below 72 F., the slider I21 will traverse theresistance I28 and thus increase the engine speed. As previouslydescribed, the engine speed will be increased and decreased in a mannerto maintain the space temperature between 70 F. and 72 F.

As weather conditions become severe, the amount of heat which canbepicked up by the outside evaporator 29 will decrease. This will resultin a smaller amount of evaporated refrigerant passing to the compressor,which would have the action of unloading the compressor. Due tothisunloading of the compressor, .the engine 5I will be unloaded andconsequently will deliver a smaller amount of waste heat. Thus at thistim when the heating load is the greatest, the reversed cycle systemtends to refuse to function thereby causing the heat supply to the spaceto begin falling off. This action will result in the space temperaturecontinuing to fall. When the space temperature falls to a value, forinstance, of 69 F., the cam I25 on shaft III will cause closure ofmercury switch 9 which will energize the magnetic clutch in thegenerator drive as follows: line wire I16, mercury switch H9, wire 94,magnetic clutch, and wire to ground. This will cause engagement of themagnetic clutch and consequently will place the generator 90 intooperation. Operation of generator 90 will cause heating of the stripheater It for thereby increasing the amount of heat supplied to thespace. Also, due to the additional load impressed upon the engine 5|,the engine will supply an increased amount of waste heat to the space.Thus, whenever the outdoor temperature becomes so low as to render thereversed cycle heating system ineflective, the electric heater I4 isplaced into operation, which has the effect of supplementing orreplacing the action of the reversed cycle system. In the event thatthis should fail to maintain the space temperature, the shaft III of theproportioning motor 0 will rotate until the cam I26 causes closing ofthe mercury switch I20. This will cause opening of the valve |0| forsupplying gas to the burner I00. This burner will be ignited by means ofany suitable type of pilot, and consequently additional heat will besupplied to the system for thereby maintaining proper temperatureconditions within the space.

The system just described, therefore, is entirely automatic in operationand serves to provide for heating, cooling, humidifying anddehumidiflcation of the space.

Figure 2 Referring to Figure 2, this figure shows a system of the samegeneral type as shown in Figure 1. In this system, however, theintermediate heat exchangers 31, GI and have been omitted and thecooling water for the condenser and internal combustion engine is passeddirectly through the air stream heaters I and 8, respectively. Also inthis system, the exhaust gases are passed. directly through the airstream heater 9'. The reversible cycle refrigeration system is exactlyth same as illustrated in Figure 1 .and consequently this system is notredescribed at this point.

Reference character 200 indicates generally a circulating pump whichcorresponds to the pump 32 of Figure 1. This pump discharges through acheck valve 201 into a supply pipe 202 which is connected by pipes 203and 204 to the cooling water inlet of the condenser l1 and to the inletof the engine water jacket, respectively. The cooling water outlet ofthe condenser is connected to a pipe ing coil '1, the outlet of which isconnected to a valve 42'. The outlet of this valve, in turn, isconnected to the inlet of the circulating pump 200 by means of a pipe205. When the valve 42' is open, it will be apparent that circulatingpump 200 will cause a circulation of cooling water from the outlet ofthe coil I through the condenser for condensing the refrigerant and backto the heating coil 'l'. The outlet of the engine water jacket isconnected by a pipe 201 to the inlet of the heating coil 8' and theoutlet of this heating coil is, in turn, connected to the coil II whichis located within the humidifier II. The outlet of the coil H is, inturn, connected to a valve 69' and this valve is, in turn, connected bya pipe 208 to the pipe 205. By this arrangement, when the valve 85' isopen, the circulating pump 200 will cause a circulation of cooling water205 which leads to the air stream heatthrough the engine and heatingcoils 0' and H back to the circulating pump.

As in th case of Figure 1, the heating coils 1' and 0' are not normallyin operation during the cooling cycle of the system, and hence it isnecessary to provide for circulating water from an outside sourcethrough the condenser l1 and the engine water jacket in order to providefor condensing of the refrigerant and cooling of the engine when thesystem is operating on the summer cycle. To this end, a water supplypipe 2|0 is connected to the discharge of the circulating pump on thedown stream side of the check valve 20|. Intel-posed in the water supplypipe 2|0 is a pressure actuated valve 2 which has a tube 2 I2 connectedto the compressor discharge line Hi. This valve may be of the type whichis biased to closed position and will remain closed until the pressureof the compressed refrigerant rises to a predetermined value. When thepressure rises to this value, the valve 2 II will begin opening andsupply water through the pipes 202 and 203 to the condenser II forthereby increasing the condensing action for maintaining the compressorhead pressure at this value. This water will be discharged from thecondenser by means of pipe 205 to which is connected a relief valve 2|3which permits the water to flow to waste or back to the source ofcooling water. During the heating cycle of the system, water supplyvalve 2| I is closed, due to valve 42' being open. At this time therelief valve 2| 3 will remain closed thereby preventing escape of thecooling water from the system.

When the valve 2 opens to admit cooling water to the condenser, it willalso admit cooling water to thewater jacket of the engine for coolingthe engine, this water then flowing through relief valve 2 to waste orback to its source.

It will be understood that if desired an electrically actuated type ofvalve such as 45 of Figure 1 may be utilized in place of valve 2 ofFigure 2, or conversely, a pressure actuated valve such as valve 2 maybe used in place of valve 45 and pressure controller 41 of Figure 1.

It will be noted that in result, the system thus far described isidentical with the corresponding portion of the system illustrated inFigure 1, that is, when the system is operating on the heating cycle,heat will be transferred from the condenser and the engine to the airstream by the coils'l' and 8', and during this time the watercirculation system will remain closed unless the pressure of thecompressed refrigerant becomes excessive, at which time water from anoutside source will be supplied to the system for cooling the condenserand the engine.

The exhaust manifold 52 of the engine 5| in this embodiment of theinvention is connected by means of a pipe-2l5 to the inlet of a threewayvalve 2|6. One outlet of the three-way valve 2|6 is connected by a pipe2|! to the exhaust heating coil 0' and the outlet. of this coil isconnected by a pipe 2|8 to the inlet of a second three-way valve 2| 9.The other outlet of the three-way valve 2|6 is connected by a pipe 220-to the pipe 2|8 and thus provides a by-pass for the exhaust gases around.the heating coil 0'. The three-way valve 2| 6 is controlled in exactlythe same manner as the corresponding valve 15 of Figure 1. Thus at thetime that valve I5 of Figure 1 would be open, the three-way valve 2l6would be positioned so as to pass the exhaust grses through the heatingcoil 5'. At the time that valve 15 of Figure 1 would be closed, however,the three-way valve 2 ll would be positioned so as to by-pass theexhaust gases around the heating coil 9.

One outlet of the three-way valve I9 is connected by a pipe 22l to aheating coil 222 which may be located, within a domestic water tank 223.The outlet of this heating coil may be connected by a pipe. 224 to asewer or chimney. The other outlet of the three-way valve 219 is'connected to a by-pass pipe 225'which leads directly to the exhaust pipe224. The three-way valve 2l9 may be controlled in accordance with thetemperature of the domestic water by means of a temperature controller226 which may be of the same type as the controller 8| of Figure 1. Thiscontroller will position the valve 219 in a manner to cause the exhaustgases to be passed through the heating coil 222 so long as thetemperature of the water is not excessive. When the domestic watertemperature becomes excessive, however, the controller 226 will causethe three-way valve 2l9 to be positioned in a manher to by-pass theexhaust gases around the heating coil 222. While I have shown thedomestic hot water heater as receiving exhaust gases which have beenpassed through the air stream heating coil 9', it will be understoodthat if desired the exhaust gases may be first passed through thedomestic water heating coil before passing to the air stream heatingcoil 9.

The controls for the system of Figure 2 may be identical with thecontrols described in detail for the system of Figure 1. Hence, nofurther description of this figure is necessary. In this case, however,it will be noted that the floating control of the area of the heatingcoils in accordance with the demand for reheat is not obtained, theheating coils either being entirely on or off.

Figure 3 In Figure 3, I have shown a modified arrange ment for heatingthe air stream by exhaust heat from the engine and for heating domestichot water. This arrangement may be employed for heating the air streamof a heating system or it may be employed for reheating in a coolingsystem, or both. For purpose of illustration, this arrangement isillustrated in conjunction with a simple summer air conditioning system.

Reference character 230 indicates a compressor which may be driven by aninternal combustion engine 23I. The compressor 23! is connected to acondenser 232, which in turn is connected to an expansion valve 233 atthe inlet of a cooling coil 234 which is located within the conditioningchamber I, the outlet of this cooling coil being connected to thecompressor intake by means of a pipe 236.

The exhaust manifold 236 of the engine is connected by a pipe 231 toheat exchanger 233. L- cated within the heat exchanger 233 may be a Thepipe 249 leading from the outlet of the coil 239 is also connected to apipe 246 which leads-to a heating coil 246 which may be located within adomestic hot water tank 241. The outlet of coil 246 is connected bymeans of a conduit 248 to the inlet of coil 239 of heat exchanger 233.Interposed in, conduit 249 is a valve 249. This valve 249 may becontrolled by means of a thermostat 259 which is responsive to thetemperature of the domestic water. So long as the water temperature isbelow a predetermined value, the controller 250 will cause the valve 249to be energized for thereby maintaining said valve open. However, whenthe space temperature becomes excessive, the controller 250 willdeenerglze valve 249 for allowing this valve to close.

From the foregoing, it will be seen that the coils 239, 2 and 246 form aclosed heat transfer system. This system is charged with a volatile heattransfer medium. When the valves 243 and 249 are open, condensed heattransfer medium will flow from the coils 2 and 246 into the coil 239 inwhich it will evaporate and pass back to the coils 241 and 246 forthereby heating the air and the domestic hot water. If the valve 243 isclosed, however, the condensed heat transfer coil 239, the upper end ofwhich may be con-' nected to a pipe 243 which leads to the inlet of aheating coil 24! located within the conditioning chamber I. Theoutletoi' this coil is connected by a conduit 242 to the inlet of thecoil 239. Interposed in 243 which may be-of the electrically actuatedtype. The valve 243 .may be controlled if desired by means of a lowlimit space temperature controller 244 which may be of any desired timand which is arranged to energize the valve 243 whenever the spacetemperature falls to a predetermined low value.

the conduit 242 is a valve medium will be prevented from leaving thecoil 24! and consequently this coil will fill up with condensed heattransfer medium which will prevent further heating of the air stream.

By the arrangement just described, the effective heating area of thereheat coil 24! will be varied in accordance with the demand for reheat.Upon a call for reheat, the thermostat 244 will cause an opening of thevalve 243 which will allow the condensed heat transfer medium to slowlytrickle from the coil 2 which will empty 3, portion of this coil andpermit vapor from the coil 233 to flow into this portion of coil 2 Therate of flow of condensate from coil 2 may be restricted when valve 243is open by means of an orifice plate or valve device such as at 242a, orthis result may be obtained by properly sizing the condensate returnpipe 242. If the demand .for reheat is relatively light, this smallportion in the thermostat 244 again opening the valve 243, allowing morecondensed heat transfer medium to flow from the coil 2. If the demandfor reheat becomes heavy, the space temperature will not rise as soon asit would if the demand were lighter and consequently more condensed heattransfer medium will be allowed to flow from the coil-24l This willincrease the effective area of the coil 24I and will cause this coiltosupply a greater amount of reheat to the space. It will thus be seenthat this arrangement provides for automatically varying the eifectiveheating surface of the reheat coil 2 in accordance-with the demand forreheat. While no receiver has been shown, it will be unders tions wherethe return lines do not have suiilcient volumetric capacity to store thenecessary volume of liquid. a receiver may be provided in the returnlines for providing the necessary storage space.

. It will be apparent that the action of the domestic hot water heatingcoil will be similar to that of the reheat coil 2. In other words, whenthat in installathe domestic water requires heating, the valve 249 willbe opened thus allowing the condensed heat transfer medium to fiow fromthe coil 246 for thereby permitting this coil to heat the domesticwater. When the domestic water is heated sufliciently, however, thevalve 249 will be closed which traps condensed heat transfer medium inthe coil 246 for thereby causing it to fill up, which will stop itsheating effect.

The engine 23| may be controlled in any desired manner and is preferablycontrolled by means of a temperature controller 25l and a humiditycontroller 252, these controllers being arranged to control aproportioning motor 253 which actuates the engine throttle valve 254.The wiring between the controllers 25l and 252 and the proportioningmotor 253 is substantially the same as indicated in Figure 1, andaccordingly, is not described here. By this arrangement,

the engine speed will be increased upon an increase in eithertemperature or humidity and the engine will operate if either thetemperature beco'mes excessive or the humidity becomes excessive. In theevent that the humidity is excessive while the temperature is fairlylow, the

operation of the cooling coil for dehumidifying will tend to reduce thetemperature of the air. The reheat control arrangement just described,however, will act to prevent this action and supply just sufficientreheat as to maintain the air temperature substantially constant.

In the foregoing description, definite values of temperature andhumidity have been mentioned in order to clearly set forth the operationof the control system. These values, however, may be varied fordifierent installations and are not to betaken as limiting.

From the foregoing detailed description, it will be apparent that I haveprovided a novel air conditioning system and control system thereforwhich acts to either cool or heat a space and which provides forautomatic control of temperature and humidity. It will also be seen thatmy system provides for heating the space during ordinary weather bymeans of a refrigeration system operating upon the reverse cycle, andadds to the heat procured in this manner, the waste heat from the enginewhich drives the compressor thereby securing extremely economicaloperation. It will also be seen that my improved system provides forsupplementing the action of the reversed cycle system or for replacingits action by means of an electric or other type of loading means forthe engine, which acts to supply additional heat to the space and tocause the engine to supply additional waste heat. Also it will be notedthat my invention provides for supplying heat from an auxiliary heaterto the space whenever the intemal combustion engine system is incapablof carrying the heating load. Due to this arrangement, the internalcombustion engine system need not be made sufficiently large to carrythe peak heating loads which occur for only a very small portion of theheating season.

While I have shown and described several embodiments of my invention,"it is obvious that many other modifications of the system andsubcombinations thereof which are within the scope of my invention willoccur to those skilled in the art, I therefore desire to be limited onlyby the scope of the appended claims as construed in the light of theprior art.

I'claim as my invention:

1. In an air conditioning system for heating and cooling a space, incombination, a reversible cycle refrigeration system adapted forselectively heating or cooling a space, said refrigeration system havinga compressor, an internal combustion engine for driving the compressor,means for placing said internal combustion engine into operation upondemand for either heating or cooling, means for transferring waste heatfrom the engine to said space, first control means for controlling thetransfer of waste heat, second control means for reversing saidrefrigeration system, and temperature responsive means acting upon fallin temperature to actuate said first control means for supplying wasteheat to the space and acting upon a further drop in temperature toactuate said second control means to reverse the system from cooling toheating.

2. In an air conditioning system for heating and cooling a space, incombination, a refrigeration system adapted for cooling a space, saidrefrigeration system having a compressor, an internal combustion enginefor driving said com pressor, means for placing said internal combustionengine into operation upon demand for either cooling or heating, controlmeans for rendering said refrigeration system effective or ineffectiveto cool said space, means for transferring jacket heat of the internalcombustion engine to said space, control means for controlling thetransfer of said jacket heat, means for transferring exhaust heat ofsaid engine to said space, control means for controlling the transfer ofsaid exhaust heat, and means for sequentially actuating saidrefrigeration system control means, said jacket heat transfer controlmeans,

and said exhaust heat transfer control means in a manner to first placeat least one of said heat transferring means into operation and thenrender the refrigeration system ineffective to cool the space.

3. In an air conditioning system for heating and cooling a space, incombination, a reversible cycle refrigeration system adapted forselectively heating or cooling a space, said refrigeration-system havinga compressor, an intemal combustion engine for driving the compressor,means for placing said internal (combustion engine into operation upondemand for either heating or cooling, control means for reversing saidrefrigeration system, means for transferring jacket heat of the internalcombustion engine to said space, control means for controlling thetransfer of said jacket heat, means for transferring exhaust heat ofsaid engine to said space, control means for controlling the transfer ofsaid exhaust heat, and means for sequentially actuating saidrefrigeration system reversing means, said jacket heat transfer controlmeans, and said exhaust heat transfer control means in a manner to firstplace at least one of said heat transferring means into operation andthen to reverse said refrigeration system from cooling to heating.

4. In an air conditioning system for heating and cooling a space, incombination, a refrigeration system adapted forcooling a space, saidrefrigeration system having a compressor, an internal combustion enginefor driving said compressor, means for placing said internal combustionengine into operation upon demand for loading the engine to increase thewaste heat output of said engine, control means for said additional loadmeans, and sequential control means acting to sequentially place saidwaste heat transferring means into operation, to render saidrefrigeration system ineffective to cool the space, and to place saidadditional load means into operation.

5. In an air conditioning system for heating and cooling 9. space, incombination, a refrigeration system adapted for cooling a space, saidrefrigeration system having a compressor, an internal combustion enginefor driving said compressor, means for placing said internal combustionengine into operation upon demand for either cooling or-heating, controlmeans for rendering said refrigeration system effective or ineffectiveto cool said space, means for transferring waste heat from said engineto said space, control means for controlling the transfer of waste heat,additional load means for said engine for loading the engine to increasethe waste heat output of said engine, control means for said additionalload means, auxiliary heating means for supplementing the heat suppliedby the system, control means for said auxiliary heating means, and meansfor actuating said control means in sequence.

6. In an air conditioning system for heating a space, in combination, areverse refrigeration system including a heat exchange device in heatexchange relationship with the space for transferring heat from a heatsource of low temperature level to said space at a higher temperaturefor heating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, heat exchangemeans separate from said first heat exchange device for transferringwaste heat from said engine to said space for supplementing the actionof said reverse refrigeration system in heating said space, and meansfor controlling the speed of said engine in accordance with the demandfor heat of said space.

7. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source at a lowtemperature level to said space at a higher temperature for heating saidspace, said refrigeration system having a compressor, driving means forsaid compressor, means for supplying waste heat from said driving meansto said space, additional means for loading said driving means heat andwaste heat to be insufficient to heat said space to the desiredtemperature.

9. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source at a lowtemperature level to said space at a higher temperature for heating saidspace, said refrigeration system having a compressor, an internalcombustion engine for driving said compressor, means for supplying wasteheat from said engine to said space, means for increasing the waste heatoutput of said engine, and temperature responsive means for placing saidlast mentioned means into and out of operation.

10. In an air conditioning system, in combination, a conditioningchamber through which air is adapted to be passed for a conditioningaction, a heating device in said chamber, said heating device having aninlet for vaporized heat transfer medium and an outlet for condensedheat transfer medium, a vapor generating device, means for connectingsaid vapor generating device to said heating device, valve means on theoutlet of said heating device for trapping condensed heat transfermedium in said device to thereby reduce the portion of said heatingdevice which is effective for heating the air, means for restrictingflow of condensed heat transfer medium from said heating means when thevalve means is open, and thermostatic means for controlling said valvemeans.

11. In an air conditioning system, in combination, a reversible cyclerefrigeration system having a condenser, an inside evaporator forcooling the space, an outside evaporator for absorbing heat for deliveryto said condenser, a compressor, valve means for selectively connectingsaid inside evaporator or said outside evaporator to said condenser andcompressor,

thereby to increase the amount of waste heat,

said additional means acting to also supply heat to the space, and meansfor placing said additional loading means into operation only when theheat demand for said space exceeds a pre determined value.

8. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source at a lowtemperature level to said space at a higher temperature for heating saidspace, said refrigeration system having a compressor, an internalcombustion engine for driving said compressor, means for supplying wasteheat from said engine to said space, additional loading means for saidinternal combustion engine, said additional load-I ing means acting toincrease the waste heat output of said engine, and means for placingsaid additional loading means into operation when the temperature ofsaid heat source falls so low as to cause the combined refrigerationsystem an internal combustion engine for driving said compressor, a heattransfer system for cooling said engine and condenser, a heat transfercircuit for transferring heat from said heat transfer system to a spacebeing conditioned, control means for controlling said engine and saidvalve means in a manner to condition said refrigeration system forheating in winter and cooling in summer, and for placing said engine inoperation upon demand for either heating or cooling, means influenced bysaid control means for passing outside cooling medium into said heattransfer system for cooling the engine and condenser during summeroperation while maintaining said heat transfer system closed duringwinter operation, additional ,load means for loading the engine toincrease the waste output thereof, and means actuated by said controlmeans for placing said additional load means into and out of operation.

12. In an air conditioning system, in combination, a conditioningchamber through which 1 air is adapted to be passed for a conditioningfheating device for trapping condensed heat transfer medium in saidheating device to thereby reduce the portion of said heating devicewhich is eifective for heating the air, means for restricting the flowof condensed heat transfer medium when the valve means is open, andthermostatic means for controlling said valve means.

13. In an air conditioning system, in combination, a. conditioningchamber through which air is adapted to be passed for a conditioningaction, a refrigeration system having a cooling and dehumidifying meansin heat exchange relationship with the air flowing through said chamberfor cooling and dehumidifying the same, a

compressor for said refrigeration system, an

internal combustion engine for driving said compressor, a reheater forreheating the air leaving said cooling and dehumidifying means, a vaporgenerator receiving heat from the internal combustion engine, means forconveying vapor from the generator to the reheater, a conduit forreturning condensate from the reheater to the generator, valve means forcontrolling circulation between said generator and said reheater, meansresponsive to excessive humidity for placing said cooling anddehumidifying means into operation, and a thermostat responsive .todemand for reheat for controlling said valve means.

14. In an air conditioning system, in combination, a conditioningchamber through which air is adapted to be passed for a conditioningaction, a refrigeration system having a cooling and dehumidifying meansin heat exchange relationship with the air flowing through said chamberfor cooling and dehumidifying thesame, a

compressor for said refrigeration system, an internal combustion enginefor driving said compressor, a reheater for reheating the air leavingsaid cooling and dehumidifying means, a vapor generator receiving heatfrom the internal combustion engine, means for conveying vapor from thegenerator to the reheater, a conduit for returning condensate from thereheater to the generator, a valve in said conduit for trappingcondensate in said reheater for thereby varying the efiective heain'ngarea of said reheater, a thermostatic controller, a humidity controller,one of said controllers controlling said cooling and dehumidifying meansand the other of said controllers controlling said valve means.

15. In a system for heating a space, in combination, a refrigerationsystem adapted for transferrlng heat from a heat source of lowtemperature level to said space at a higher temper-' ature level forheating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, heat exchangemeans for delivering waste heat from the engine to said space,additional loading means for loading said engine, and thermostatic meansresponsive to the demand for heat of said spacefor starting said enginein response to an initial demand for heat, for increasing the enginespeed as the demand for heat increases, and

for placing said additional loading means into operation upon furtherincrease in heat demand.

16. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source of lowtemperature level to said space at a higher temperature level forheating the space, said refrigeration system having acompressor, aninternal combustion engine for driving said compressor, heat exchangemeans for delivering waste heat increase in heat demand.

17. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source of lowtemperature level to said space at a higher temperature level forheating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, heat exchangemeans for delivering waste heat from the crater driven by said engine,an electric heater receiving power from said generator for additionallyheating the space, a switch for controlling said electric heater, andthermostatic means responsive to the heat demand for the space forstarting said engine in response to an initial demand for heat, forincreasing the engine speed in response to increase in demand for heatand for closing said switch to place said electric heater into operationupon further increase in heat demand.-

18. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source of lowtemperature level to said space at a higher temperature level forheating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, heat exchangemeans for delivering waste heat from the engine to said space, a wasteheat controller for increasing the waste heat output of the engine,automatic starting means for the engine, a speed controller for saidengine, theran initial demand for heat and to increase the engine speedupon an increase in demand for heat, and means for actuating said wasteheat controller in a manner to increase the waste heat of the enginewhen the combined refrigeration system heat and normal waste heat of theenlue is insufiicient.

19. In a system for conditioning a space and providing a supply ofheated medium, in combination, a refrigeration system for conditioningthe air in said space, said refrigeration system including a compressor,an internal combustion engine for dri g said compressor, automaticstarting means for said engine, a speed controller for said engine,thermostatic means responsive to space temperature for controlling saidautomatic starting means and said speed controller, a heat exchanger forheating said medium, thermostatic means-for supplying waste heat fromthe engine to said space and to said heat exchanger, a controller forincreasing the waste heat from the engine, and thermostatic means foractuating said last mentioned controller for increasing the supply ofwaste heat from the engine when the normal supply is insuflicient.

20. In a system for conditioning a space and providing a supp y ofheated medium, in combination, a refrigeration system for conditioningthe air in said space, said refrigeration system including a compressor.

engine for driving said compressor, automatic engine to said space, anelectric genan internal combustion I starting means for said engine, aspeed controller for said engine, thermostatic means responsive to spacetemperature for controlling said automatic starting means and saidspeedcontroller, a heat exchanger for heating said medium meansincluding thermostatic means infiuenced by the demand for heat of saidmedium for supplying waste heat from the engine to said medium, acontroller for increasing the waste heat from the engine, andthermostatic means for actuating said last mentioned controller in amanner to increase the supply of waste heat from the engine when thenormal supply is insufficient.

21. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source of lowtemperature level to said space at a higher temperature level forheating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, means includinga heat exchanger through which exhaust gases of th engine are passed fortransferring exhaust heat from the engine to said space, a fuel burnerfor adding additional gases of combustion to the exhaust gases passingthrough said heat exchanger, and thermostatic means for placing saidburner in operation when the refrigeration system heat and the exhaustheat is insufficient to heat said space.

22. In a system for heating a space, in combination, a refrigerationsystem adapted for transferring heat from a heat source of lowtemperature level to said space at a higher temperature level forheating the space, said refrigeration system having a compressor, aninternal combustion engine for driving said compressor, heat exchangemeans for delivering waste heat from the engine to said space, auxiliaryheating means for supplying heat to said space in addition to the heatsupplied by said refrigeration system and said waste heat, automaticstarting means for said engine, a speed controller for said engine,thermostatic means for controlling said automatic starting means andsaid speed controller in a manner to start said engine upon an initialcall for heat and to increase the speed of the engine as the heat demandincreases, and means for placing said auxiliary heating means intooperation when the combined waste heat and refrigeration system heat isinsuflicient to heat said space.

23. In an air conditioning system, in combination, a reversible cyclerefrigeration system for heating and cooling a space, said refrigerationsystem including a condenser for dissipating heat during the coolingcycle and for delivering heat to the space during the heating cycle, aheat exchanger in heat exchange relationship with the space, a normallyclosed heat transfer circuit between said condenser and said heatexchanger comprising a supply conduit for conveying heat transfer mediumfrom said condenser to said heat exchanger and a return conduit forreturning said medium to said condenser, a supply connection forsupplying heat transfer medium to said return conduit, a check valve insaid return conduit to prevent heat transfer medium admitted from saidsupply connection from passing through said return conduit to said heatexchanger, and a relief connection in said supply conduit for allowingmedium passed into said heat transfer circuit by said supply connectionto escape from said heat transfer circuit after passing through saidcondenser.

ALWIN B. NEWTON.

